Image transfer mechanism



Dec. 29, 1970 0, w, GNAGE 3,551,045

IMAGE TRANSFER MECHANISM Filed July 1, 1968 OLIVER w GNAGE INVENTOR. 1% J1 0 4L444 fwwm ATTORNEYS Patented Dec. 29, 1970 3,551,046 IMAGE TRANSFER MECHANISM Oliver W. Gnage, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed July 1, 1968, Ser. No. 741,387 Int. Cl. G03g 15/00 US. Cl. 355-4 4 Claims ABSTRACT OF THE DISCLOSURE In an electrostatic tone image transfer device, separate, photoconductive chips, after development of toner images thereon, are brought into registration at a transfer station against registration pins which space the chips at a dis tance equal to the circumference of a circle having a radius equal to the sum of the radius of a transfer roller and the thickness of the receiver sheet thereon. With this spacing, when the transfer roller is rotated by a rack and gear arrangement as it moves along a transfer path across the register chips an electrostatic toner image on each of the chips is transferred in registry onto the receiver sheet.

CROSS-REFERENCE TO RELATED APPLICATION The apparatus of this invention may be utilized in the device disclosed in commonly assigned US. patent application, Ser. No. 741,359, filed July 1, 1968, and entitled Printing Apparatus to John S. Pollock.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a transfer device for the transfer of electrostatic toner images fromthe surface of a photoconductive component to a receiving surface, and more particularly to such a device for transferring images from a plurality of photoconductive components onto a single receiving surface in registry.

Description of the prior art The problem of registering electrostatic toner images has been largely ignored because in most instances only one image was transferred to each receiver. Most attempts to superimpose a plurality of toner images involve trying to precisely align optical systems for three color separation images with the position of exposure stations and separate transfer stations to provide exact alignment of electrostatic toner images on a receiver to obtain registry. However, as a practical matter, these methods are not very satisfactory because of extreme difiiculty in maintaining all parts in proper alignment at all times. Thus, the need for a convenient way of aligning each photoconductor with the receiver for each transfer of an image is apparent.

This alignment problem is of particularly importance in copying color originals. In the usual electrophotographic process, an original, such as a color negative, is broken down into its three color components by the use of beam splitters, filters, etc. as is well known in the art. Color-separation images thus formed are then projected on to different photoconductive surfaces to form three separate electrostatic images. These images are each toned with a toner having a complementary color to each color separation image. The toned images are finally transferred in registry to a receiver to form a composite color print. Unless the registration of the toner images is held within very narrow limits, the resulting print will be unsatisfactory.

SUMMARY OF THE INVENTION In the present invention, photoconductive chips are fed from separate developing stations into engagement with registration means at a transfer station. The registration means are spaced so that distance between corresponding points on adjacent photoconductive chips is equal to the circumference of a circle having a radius equal to the sum of the radius of a transfer roller and the thickness of a receiver attached thereto. Thus, the transfer roller will make exactly one revolution between the beginning of one transfer and the beginning of the next transfer. The transfers are made as the transfer roller is moved across the photoconductive chips and rotatably driven by a gear and rack arrangement. Because of the relationship between the size of the transfer roller and the spacing of the chips, the toner image on each chip can be transferred to the receiver in registry.

Additional novel features of this invention will become apparent from the description which follows.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a fragmentary perspective view showing a carriage mechanism for transporting the chips to a transfer station and a transfer mechanism for causing a toner image to be transferred from each chip to a receiver in registry.

DESCRIPTION OF THE PREFERRED EMBODIMENT In an electrophotographic device for making composite prints from a single device, separate photoconductive surfaces are charged and exposed to separate images, such as color separation images, to form corresponding electrostatic images thereon The photoconductors then pass through developing stations which tone the electrostatic images for subsequent transfer to a single receiver in registry to make a composite print.

In accordance with this invention, a carriage transport mechanism C is provided, as in the drawing, having a plurality of carriages 10, 10' and 10" attached to timing belts 11, 11 and 11", respectively, which are driven as shown by motor 12 through endless belt 13. Each carriage supports a photoconductive chip 14 and is moved across developing stations 15, 15 and 15", respectively, to a transfer station T where they are brought into engagement with alignment means, such as registration pins 16. Advantageously, these pins are positioned to space the chips at a distance which. is equal to the circumference of a circle having a radius equal to the sum of the radius of transfer roller 17 and the thickness of receiver 18 attached to the transfer roller. Stated another way, this distance is equal to the circumference of a cylinder formed by revolving a receiver on the transfer roller about the roller as a center.

Transfer roller 17 is rotatably mounted in a frame 19 which is attached to a timing belt 21 driven by a motor 22 through endless belt 23, as shown. A pitch ring '24 is provided at one end of roller 17 and has a height at least equal to the thickness of receiver 18. This ring rides on rail 25 to provide the proper spacing between the chip and paper during transfer. A gear 26, at the same end, engages rack 27 on rail 25 so that the transfer roller, which is driven by timing belt 21 along rails 28 and 2.9 and across the photoconductive chips, will be caused to rotate in a counterclockwise direction as viewed in the drawing. This movement will bring receiver 18 into rolling contact or near-contact with the photoconductive surface of chip 14 as determined by the height of ring 24 so that a toner image thereon will be transferred to the receiver.

Because of the advantageous spacing of the chips, trans. fer of the images from each photoconductor may be made in superimposed aligned relationship onto receiver 18 to form a composite print, such as a color print. Of course, it will be understood that a roller segment rather than a complete roller may be used, so long as the segment length is at least as long as the receiver supported thereon.

From the foregoing, the novel features and advantages of this invention are readily apparent. A transfer mechanism has been provided wherein a plurality of electrostatic toner images may be transferred to a receiver in registry. This is accomplished by positioning the registration pins so that at a distance equal to the circumference of a circle whose radius is equal to the radius of the roller plus the thickness of the receiver.

The invention has been described in detail with particular reference to a preferred embodiment thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

I claim:

1. A transfer mechanism for transferring, in registry electrostatic toner images from each of a plurality of photoconductive chips onto a single receiver, the receiver having a thickness, said mechanism comprising:

transfer means having a cylindrical portion for supporting said receiver during transfer;

separate registration means for aligning each of said chips, said registration means being positioned so that corresponding portions of the toner images thereon are spaced at a distance equal to the circumference of a circle having a radius equal to the sum of the radius of said cylindrical portion and the thickness of said receiver;

means for moving said chips into engagement with said registration means; and

means for moving said transfer means across said photoconductive chips, while said chips are in engagement with said registration means, so that said receiver sequentially engages each of said photoconductive chips in rolling contact to transfer each of said toner images to said receiver in registry.

2. A transfer mechanism, as claimed in claim 1, wheresaid transfer means is a cylindrical roller.

3. A transfer mechanism, as claimed in claim 1, wherein said means for moving said transfer means across said photoconductive chips includes:

a gear at least one end of said transfer roller; and

a rack extending along one side of said registration means and positioned for engagement by said gear to cause positive rotation of said transfer roller as it moves across said photoconductive chips to facilitate transfer of said toner image to said receiver.

4. A transfer mechanism for transferring, in registry, electrostatic toner images from each of a plurality of photoconductive chips onto a receiver, having an outer surface said mechanism comprising:

a transfer roller having a cylindrical segment for supporting said receiver during transfer;

separate registration means for positioning each of said chips, said registration means being positioned so that corresponding portions of the toned images thereon are at a distance from each other equal to the circumference of a cylinder defined by rotating the outer surface of said receiver about the center of said cylindrical segment;

means for moving said chips into engagement with said registration means; and

means for moving said transfer roller across said photoconductive chips, while said chips are in engagement with said registration means, so that said receiver sequentially engages each of said photoconductive chips in rolling contact to transfer each of said toner images to said receiver in registry.

References Cited UNITED STATES PATENTS 3,357,830 12/1967 Bixby l17-l7.5X 3,399,611 9/1968 Lusher 355-4 JOHN M. HORAN, Primary Examiner R. P. GREINER, Assistant Examiner U.S. Cl. X.R. 

